Antiparallel (AP) pinned spin valve sensor with giant magnetoresistive (GMR) enhancing layer

Abstract

The present invention is an external field stabilized and near zero magnetostrictive double spin valve sensor with giant magnetoresistive (GMR) enhancing, antiparallel pinned and sense current field pinned layers. In a preferred embodiment of the invention the AP pinned layer has first and second films that are made of cobalt iron (Co 90 Fe 10 ). In order to enhance the spin dependent scattering first and second GMR enhancing layers are employed which are also constructed of cobalt iron (Co 90 Fe 90 ). Further, in order to double the spin valve effect a sense current field (SCF) pinned layer is employed which is pinned in the same direction as the second film of the AP pinned layer. The SCF pinned layer is also constructed of cobalt iron (Co 90 Fe 10 ). In the preferred embodiment all of the magnetic layers are constructed of cobalt iron (Co 90 Fe 10 ) so that their magnetic moments are returned to their original positions after the occurrence of an external field. Further, the cobalt iron (Co 90 Fe 10 ) has near zero magnetostriction so that stress induced anisotropy does not alter the magnetic properties of these layers. The high resistance of cobalt iron (Co 90 Fe 10 ) in the AP pinned layer and the SCF pinned layer ensures that a minimum amount of sense current field is shunted.

I claim: 
     
       1. A spin valve sensor comprising: a ferromagnetic free layer;   a nonmagnetic electrically conductive first spacer layer;   an antiparallel (AP) pinned layer;   an antiferromagnetic pinning layer;   the AP pinned layer being exchange coupled to the pinning layer and the first spacer layer being located between the AP pinned layer and the free layer;   the AP pinned layer including first and second ferromagnetic films and an AP coupling film wherein the AP coupling film is sandwiched between the first and second ferromagnetic films; and   at least one of the ferromagnetic films being Co 90  Fe 10 .   
     
     
       2. A spin valve sensor as claimed in claim 1 wherein each of the first and second ferromagnetic films is Co 90  Fe 10 . 
     
     
       3. A spin valve sensor as claimed in claim 2 including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       4. A spin valve sensor as claimed in claim 2 including: a nonmagnetic electrically conductive second spacer layer;   a sense current field (SCF) pinned layer; the second spacer layer being sandwiched between the free layer and the SCF layer; and   the SCF layer being Co 90  Fe 10 .     
     
     
       5. A spin valve sensor as claimed in claim 4 including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       6. A spin valve sensor comprising: a ferromagnetic free layer;   a nonmagnetic electrically conductive first spacer layer;   an antiparallel (AP) pinned layer;   an antiferromagnetic pinning layer; the AP pinned layer being exchange coupled to the pinning layer and the first spacer layer being located between the AP pinned layer and the free layer;   the AP pinned layer including first and second ferromagnetic films and an AP coupling film wherein the AP coupling film is sandwiched between the first and second ferromagnetic films;     a nonmagnetic electrically conductive second spacer layer;   a sense current field (SCF) pinned layer; the second spacer layer being sandwiched between the free layer and the SCF layer; and   the SCF pinned layer being Co 90  Fe 10 .     
     
     
       7. A spin valve sensor comprising: a ferromagnetic free layer;   a nonmagnetic electrically conductive first spacer layer;   an antiparallel (AP) pinned layer;   an antiferromagnetic pinning layer; the AP pinned layer being exchange coupled to the pinning layer and the first spacer layer being located between the AP pinned layer and the free layer;   the AP pinned layer including first and second ferromagnetic films and an AP coupling film wherein the AP coupling film is sandwiched between the first and second ferromagnetic films; and   each of the first and second ferromagnetic films being Co 90  Fe 10       a nonmagnetic electrically conductive second spacer layer;   a sense current field (SCF) pinned layer; the second spacer layer being sandwiched between the free layer and the SCF layer; and   the SCF layer being Co 90  Fe 10  ;   the free layer having a film of nickel iron (NiFe) and a third and fourth ferromagnetic films of Co 90  Fe 10  with the film of nickel iron (NiFe) being sandwiched between the third and fourth ferromagnetic films of Co 90  Fe 10  ;   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer and the fourth ferromagnetic film of Co 90  Fe 10  interfacially engaging the second spacer layer.     
     
     
       8. A magnetic head that has an air bearing surface (ABS) comprising: a read head that includes: first and second ferromagnetic shield layers:   first and second nonmagnetic electrically insulative gap layers located between the first and second ferromagnetic shield layers; a spin valve sensor responsive to applied magnetic fields;     the spin valve sensor being located between the first and second gap layers; and   first and second electrically conductive lead layers located between the first and second gap layers and connected to the spin valve sensor for conducting a sense current through the spin valve sensor; the spin valve sensor including:     a pinning layer that has magnetic spins oriented in a first predetermined direction that is perpendicular to the ABS;   an antiparallel (AP) pinned layer exchange coupled to the pinning layer so that a magnetic moment of the AP pinned layer is pinned in a second predetermined direction that is antiparallel to said first predetermined direction; the AP pinned layer including first and second ferromagnetic films and an AP coupling film wherein the AP coupling film is sandwiched between the first and second ferromagnetic films; and   each of the first and second ferromagnetic films being Co 90  Fe 10  ;   a free layer that has a magnetic moment that is free to rotate relative to the second predetermined direction of the AP pinned layer in response to an applied field;   a nonmagnetic electrically conductive first spacer layer;   the first spacer layer being located between the free layer and the AP pinned layer.       
     
     
       9. A magnetic head as claimed in claim 8 including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       10. A magnetic head as claimed in claim 9 including: the free layer having a fourth ferromagnetic film of Co 90  Fe 10  wherein the film of nickel iron (NiFe) is sandwiched between the third and fourth films of Co 90  Fe 10  ;   the fourth film of Co 9  Fe 10  interfacially engaging the second spacer layer.   
     
     
       11. A magnetic head as claimed in claim 8 further including: a sense current field (SCF) pinned layer that has a magnetic moment that can be pinned in a direction parallel to said second predetermined direction by a sense current field from other conductive layers of the spin valve sensor;   a nonmagnetic electrically conductive second spacer layer that is located between the free layer and the SCF pinned layer; and   the SCF pinned layer being Co 90  Fe 10 .   
     
     
       12. A magnetic head as claimed in claim 11 including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       13. A magnetic head as claimed in claim 12 including: the free layer having a fourth ferromagnetic film of Co 90  Fe 10  wherein the film of nickel iron (NiFe) is sandwiched between the third and fourth films of Co 90  Fe 10  ;   the fourth film of Co 90  Fe 10  interfacially engaging the second spacer layer.   
     
     
       14. A magnetic head as claimed in claim 8 further including: a write head including: first and second pole piece layers and a write gap layer;   the first and second pole piece layers being separated by the write gap layer at the ABS and connected at a back gap that is recessed rearwardly in the head from the ABS;   an insulation stack having at least first and second insulation layers;   at least one coil layer embedded in the insulation stack; and   the insulation stack and the at least one coil layer being located between the first and second pole piece layers.     
     
     
       15. A magnetic head as claimed in claim 14 including: a sense current field (SCF) pinned layer that has a magnetic moment that can be pinned in a direction parallel to said second predetermined direction by a sense current field from other conductive layers of the spin valve sensor;   a nonmagnetic electrically conductive second spacer layer that is located between the free layer and the SCF pinned layer; and   the SCF pinned layer being Co 90  Fe 10 .   
     
     
       16. A magnetic head as claimed in claim 15 including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       17. A magnetic head as claimed in claim 16 including: the free layer having a fourth ferromagnetic film of Co 90  Fe 10  wherein the film of nickel iron (NiFe) is sandwiched between the third and fourth films of Co 90  Fe 10  ;   the fourth film of Co 90  Fe 10  interfacially engaging the second spacer layer.   
     
     
       18. A magnetic disk drive that includes at least one magnetic head that has an air bearing surface (ABS), the disk drive comprising: the magnetic head including a combined read head and write head;   a read head that includes: first and second ferromagnetic shield layers: first and second nonmagnetic electrically insulative gap layers located between the first and second ferromagnetic shield layers;   a spin valve sensor responsive to applied magnetic fields;   the spin valve sensor being located between the first and second gap layers; and   first and second electrically conductive lead layers located between the first and second gap layers and connected to the spin valve sensor for conducting a sense current through the spin valve sensor;       the spin valve sensor including: a pinning layer that has magnetic spins oriented in a first predetermined direction that is perpendicular to the ABS;   an antiparallel (AP) pinned layer exchange coupled to the pinning layer so that a magnetic moment of the AP pinned layer is pinned in a second predetermined direction that is antiparallel to said first predetermined direction; the AP pinned layer including first and second ferromagnetic films and an AP coupling film wherein the AP coupling film is sandwiched between the first and second ferromagnetic films; and   each of the first and second ferromagnetic films being Co 90  Fe 10  ;   a free layer that has a magnetic moment that is free to rotate relative to the second predetermined direction of the AP pinned layer in response to an applied field;   a nonmagnetic electrically conductive first spacer layer;   the first spacer layer being located between the free layer and the AP pinned layer;       the write head including: first and second pole piece layers and a write gap layer;   the first and second pole piece layers being separated by the write gap layer at the ABS and connected at a back gap that is recessed rearwardly in the head from the ABS; an insulation stack having at least first and second insulation layers;   at least one coil layer embedded in the insulation stack; and   the insulation stack and the at least one coil layer being located between the first and second pole piece layers;     the second shield layer and the first pole piece layer being a common layer;   a housing;   a magnetic disk rotatably supported in the housing;   a support mounted in the housing for supporting the magnetic head with its ABS facing the magnetic disk so that the magnetic head is in a transducing relationship with the magnetic disk;   means for rotating the magnetic disk;   positioning means connected to the support for moving the magnetic head to multiple positions with respect to said magnetic disk; and   processing means connected to the magnetic head, to the means for rotating the magnetic disk and to the positioning means for exchanging signals with the merged magnetic head, for controlling movement of the magnetic disk and for controlling the position of the magnetic head.     
     
     
       19. A magnetic disk drive as claimed in claim 18 including: a sense current field (SCF) pinned layer that has a magnetic moment that can be pinned in a direction parallel to said second predetermined direction by a sense current field from other conductive layers of the spin valve sensor;   a nonmagnetic electrically conductive second spacer layer that is located between the free layer and the SCF pinned layer; and   the SCF pinned layer being Co 90  Fe 10 .   
     
     
       20. A magnetic disk drive as claimed in claim 19 wherein the processing means is connected to the first and second leads for applying the sense current to the sensor in a direction that causes conductive layers of the sensor to apply sense current fields to the antiparallel pinned layer that are directed in said first predetermined direction and sense current fields to the SCF pinned layer that are directed in said second predetermined direction. 
     
     
       21. A magnetic disk drive as claimed in claim 20 wherein the processing means applies said sense current. 
     
     
       22. A magnetic disk drive as claimed in claim 18 further including: the free layer having a film of nickel iron (NiFe) and a third ferromagnetic film of Co 90  Fe 10  ; and   the third ferromagnetic film of Co 90  Fe 10  interfacially engaging the first spacer layer.   
     
     
       23. A magnetic disk drive as claimed in claim 22 including: the free layer having a fourth ferromagnetic film of Co 90  Fe 10  wherein the film of nickel iron (NiFe) is sandwiched between the third and fourth films of Co 90  Fe 10  ;   the fourth film of Co 90  Fe 10  interfacially engaging the second spacer layer.   
     
     
       24. A magnetic disk drive as claimed in claim 23 including: a sense current field (SCF) pinned layer that has a magnetic moment that can be pinned in a direction parallel to said second predetermined direction by a sense current field from other conductive layers of the spin valve sensor;   a nonmagnetic electrically conductive second spacer layer that is located between the free layer and the SCF pinned layer; and   the SCF pinned layer being Co 90  Fe 10 .   
     
     
       25. A magnetic disk drive as claimed in claim 24 wherein the processing means is connected to the first and second leads for applying the sense current to the sensor in a direction that causes conductive layers of the sensor to apply sense current fields to the antiparallel pinned layer that are directed in said first predetermined direction and sense current fields to the SCF pinned layer that are directed in said second predetermined direction. 
     
     
       26. A magnetic disk drive as claimed in claim 25 wherein the processing means applies said sense current.